The prior art teaches the use of many different polymeric materials in contact lenses. However, although these polymers possess the optical clarity necessary for corrective lenses, they suffer from other characteristics which reduce their potential utility.
Poly(methyl methacrylate) is rigid and durable but relatively impermeable to oxygen. The hydrogel materials based on hydrophilic polymers such as poly (hydroxyethyl methacrylate) are desirably soft but have poor durability because of the relatively weak gel structure. In addition, it is suspected that they provide an environment which is favorable for bacterial growth. Further, such hydrogel materials are relatively impermeable to oxygen unless the water content of the gel is very high.
Silicone rubber is soft and resilient and is highly permeable to oxygen. However, due to the low strength of polysiloxanes, a filler which increases the refractive index of the material must be added to improve the durability.
More recently, contact lenses made from a copolymer of a fluoralkyl acrylic ester and an alkyl acrylate or methacrylate, such as disclosed in Gaylord U.S. Pat. No. 3,808,179, have been developed. These lenses have improved oxygen permeability when compared to lenses formed of poly(methyl methacrylate); and some of them are stated in the patent to be water-wettable.